The overall objective of this project are to determine the dosage and monitoring procedures through refinement of techniques and instrumentation of microwave irradiation by measuring modulated and pulse transmission of two frequency (2450 plus or minus 50 megahertz and 915 plus or minus 25 megahertz) and 2 power ranges; to determine exposure levels that do and do not result in embryopathy chronic exposure of pregnant rats at low dose levels of microwave irradiation through pregnancy, during the implantation period, during the organogenic period, and during the fetal period. The specific objective is a) to determine possible increases in rates of embryotoxicity or abnormal offspring and to determine how the threshold dose may vary with different types of microwave exposure and different embryopathies b) to determine whether the reproductive performance following in utero or adult exposure is indeed a sensitive measure of microwave exposure c) to determine whether central nervous system will manifest functional or architectural alterations following in utero microwave irradiation, d) to attempt to compare the threshhold sensitivity of behavioral changes with observable anatomic or histologic changes in the embryo.